The present invention relates to connectors for electrical conductors, and more particularly, to connectors for joining high density conductors such as found on printed circuit boards, with corresponding contacts on flexible circuits.
As the size and/or complexity of circuit components and their associated printed or etched circuit conductors continue to be miniaturized, the size of the contacts for interconnecting components has also decreased. Conventional spring biased connectors can no longer be effectively used under these circumstances. U.S. Pat. No. 4,968,265, issued Nov. 6, 1990 for "Fluidly Actuated Electrical Connector", and U.S. Pat. No. 5,002,496, issued Mar. 26, 1991 for "Cam Actuated Electrical Connector", represent significant improvements to earlier connectors, by establishing and maintaining electrical contact between conductive members to be joined, without inherent minimum line and space limitations that depend upon the spring characteristics of the mating contact structures. These patents describe the implementation of so-called "hydrostatic connector" techniques, which utilize a fluid bladder interacting between a backing member and the conductors, whereby the bladder forms a compliant membrane surface that transmits force uniformly from the backing member to the flexible circuit, forcing contact pads on the flex circuit to mating pads on the PCB such that a high integrity electrical connection is realized. The disclosures of these two patents are hereby incorporated by reference.
Although the various embodiments described in the patents mentioned immediately above, can perform satisfactorily, the actuation mechanisms are not well integrated with the connector, resulting in a significant increase in manufacturing costs, as well as occupying space which could otherwise be utilized for further miniaturization and compacting of components.
Some efforts have been made to improve these deficiencies, as represented by the Hydro Flex.TM. connector system from Synapse Technologies, Inc. This system is made up of two functional parts, a controlled-impedance flex circuit with ground-plane, gold contact pads, and a molded beam force generator containing a sealed, fluid-filled bladder. When actuated, the beam is deflected and the bladder forces pads on the flex circuit against mating pads on e.g., a PCB, providing uniform normal force and virtually zero shear force. This connector system is tolerant of variations in board thickness and flatness, and maintains a gas tight seal over a wide temperature range. Contact densities of up to 100 per inch are achieved on a single sided stacking configuration, and up to 200 per inch in a double sided right angle version. Although the actuation scheme in the Hydro Flex.TM. connector was simplified relative to that disclosed in the two patents identified above, the technique for actuating the beam to energize the bladder against the pads on the flex circuit and against pads on the PCB, did not allow contact pad wipe.